Dispersive Delay Lines Using 180° Reflecting Metal Dot Arrays

Abstract

Recently, a reflective array compressor using 180' grooved reflectors and a 3dB multistrip coupler has been described. This has the advantage over conventional 90' reflective devices that the surface waves undergo only one reflection instead of two, and so the insertion loss can be low. This Taper reports a new device in which the grooves are replaced by metal dot arrays, removine the need for ion-beam milling and - through variation of dot density - providing a simple method of weighting. Compared with dot array devices using 90' reflectors the design is simplified since the velocity and scattering anisotropy, important for 90' reflectors, need not be considered. under the metal dot array is potentially a source of phase error, but it is shown that a simple empirical correction in the mask design is sufficient to reduce this to an acceptable level. The SAW velocity change